Casing perforator



Oct. 19, 1965 o. w. FROGGE CASING PERFORATOR Filed April e, 1965 PWC-3.3

FIG. 4

QTTIS vv. FROGGE INVENTOR.

G 2 F AH 4.. IVA. mm [ULI x @nlllnw I J e IMNTV United States Patent O3,212,580 CASING PERFORATOR Ottis W. Frogge, P.O. Box 8183, OklahomaCity 14, Okla. Filed Apr. 8, 1963, Ser. No. 271,389 s Claims. (Cl.16s-55.3)

The present invention relates to oil field tools and more particularlyto a casing perforator.

It is desirable in many oil wells to increase the oil recovery therefromby perforating the casing and simultaneously perforating the cementsurrounding the casing to open up a channel into an oil bearingformation through which the oil may enter the casing.

The prior art reveals a plurality of different types of casingperforators. A popular type perforator presently used preforms a casingperforating action by the use of explosive charges which forces abullet-like projectile outwardly through the casing Wall.

The above mentioned bullet-type projectile perforators perform thisfunction but the apertures formed in the casing wall, the surroundingcement and the oil bearing formation is relatively small andconsequently easily plugged. After perforating the casing of an oilwell, it is usually advisable to acidize or fracture the formation toopen up the channels thus formed for the entrance of oil or gas into thecasing.

It is, therefore, the principal object of the present invention toprovide a casing perforator which will perforate the casing wall andsurrounding cement and form an opening therethrough of substantal size.

Another object is to provide a tool of this class which is provided withantifriction means so that the casing perforating act may be more easilyaccomplished.

Another object is to provide a casing perforator which may be run on theend of a tubular string or on a wire line.

Another object is to provide a tool which, when connected with a tubularstring, provides means for circulating fluid downwardly through thetubular string and tool.

Still another object is to provide a tool which may be indexed whilestill in the hole to perforate a plurality of horizontally alignedapertures spaced 120 apart.

Yet another object is to provide a casing perforator which remains ininoperative position while going in the hole and which may thereafter betripped for performing the casing perforating action and, afterperforating the casing, may be reset in neutral or inoperative positionfor the removal of the tool.

The present invention accomplishes these and other objects by providingan elongated body having a casing perforating blade slidably carried forvertical movement with respect to the tool and including antifrictionmeans for vertical movement of the tool during the perforating action.

Other objects will be apparent from the following description when takenin conjunction with the accompanying single sheet of drawings, wherein:

FIGURE l is a vertical cross-sectional view of the tool, partly inelevation, and illustrating, by dotted lines, the casing perforatingaction;

FIGURE 2 is a fragmentary vertical cross-sectional view takensubstantially along the line 2--2 of FIG. l;

FIGURES 3 and 4 are horizontal cross-sectional views, to an enlargedscale, taken substantially along the respective lines 3-3 and 4-4 ofFIG. 1; and,

FIGURE 5 is a fragmentary vertical cross-sectional view, partly inelevation, of an alternate embodiment of the depending end portion ofthe device.

Like characters of reference designate like parts in those figures ofthe drawings in which they occur.

3,212,580 Patented Oct. 19, 1965 In the drawings:

The reference numeral 10 indicates the device, as a whole, which iscylindrical in general configuration and includes a body portion 12 andguide means 14. The reduced upwardly disposed end portion of the body 12is provided with a tool joint 16 for threadedly connecting the body toan adapter 17 which is in turn connected to the depending end of atubular string or a wire line, neither of which is shown. An elongatedlongitudinal cutter or blade carrier slot 18 is formed in the toolintermediate its ends. The bottom of the slot 18 extends downward andinwardly from the outer surface of the upper end of the body terminatingin an abrupt end or shoulder 20 spaced above the depending end of thebody. A bearing groove 19, coextensive with the slot 18, is formed inthe body 12 in communication with the slot 18 and perpendicular to itslongitudinal axis thus defining a substantial T-shaped opening 22 whenviewed in horizontal cross section (FIG. 3) for the purposes which willpresently be apparent.

As shown in FIGS. 1 and 2 the slot 18 is parallel to the longitudinalaxis of the body 12 and opens outwardly of the body throughout itslength. The T-shaped bottom portion of the slot extends diagonally withrespect to and intersects the longitudinal axis of the body.

Adjacent its respective end portions and diametrically opposite thecutter opening 22 the body is provided with a transverse recess orsocket 24 for journaling an antifriction roller 26 on a bearing equippedhorizontal axle 28. The rollers 26 are provided with an arcuate orbulging periphery, preferably having a contour conforming to an arc ofthe inner periphery of the casing to be perforated. The function of therollers is to reduce the frictional contact between the body 12 and theeasing wall during the casing perforating act as more fully describedhereinbelow.

A cutter or perforating knife 30 comprising a blade portion 32 and aT-shaped base portion 34 is cooperatively received slidably by theT-shaped opening 22. The blade portion 32 is formed of hardened materialhaving parallel side surfaces and outwardly convergent upper and lowersurfaces defining a sharpened edge or tip 36. The relative size orlength of the knife 30, with respect to the opening 22, is such that theknife edge 36 lies inwardly of the circumferential plane of the body 12when the knife is in its lowermost retracted position. A keeper plate37, having a dove tail-shaped base 37A cooperatively received by asimilarly shaped groove extending transversely across the opening 22,removably maintains the knife 30 in place.

The guide means 14 includes a tube member 38 of selected diameter,preferably relatively small when compared with the body 12, which isthreadedly connected at its upper end to the depending end of the body.An enlarged nut 40, having a tapered and threaded exterior, is securedto the depending end of the tube 38. A conventional spring equippedwiper unit 42, having upper and lower collars 42A and 42B, respectively,slidably surrounds the tube 38. The lower collar 42B is cooperativelythreaded for engagement with the nut 40.

A mandrel or plunger 44 is slidably received for vertical movementthrough the lower end portion of the body 12 by an aperture 46 so thatthe mandrel 44 normally extends downwardly below the lower end of thebody a selected distance. A flattened surface or groove 45 formed on themandrel 44, intermediate its ends, cooperates with a set screw 48 andpermits vertical movement of the mandrel. The upper end of the mandrel44 normally is positioned against the knife 30 when the latter is in itslower or retracted position. A plurality, preferably three, verticalgrooves or slots 50 are formed ...n in the upper end portion of theperiphery of the tube 38 in 120 spaced relation. A spring urged pin 52,extending through the wall of the uppermost collar 42A, engages theslots 50 to index the tool as is more fully explained hereinbelow.

In order to provide fluid circulation through the device 10 the body 12is centrally bored at its upper and lower ends, as at 54 and 55. Thebore 55 communicates with the bore of the tubular member 38. The body 12is further provided with vertical extending diametrically opposingchannels or slots 56 on its opposing sides, spaced 90 with Irespect tothe knife slot 22, and communicating at their respective upper and lowerends with the bores 54 and S5 by horizontal or transverse bores 57 and5S, respectively, which intersect the respective central bores `54- and55 thus permitting fluid circulation through the tool.

An alternate embodiment of the guide means is illustrated in FIG. foruse when running the device on a wire line wherein the depending end ofthe tube 38 is provided with a ring :or washer 60 rigidly secured, as bywelding, to the periphery of its -depending end portion. In thisembodiment the nut 40 is not secured to the tube 38 but looselysurrounds the latter. The depending end portion of the nut 40 iscounterbored to receive the ring 60 thus permitting rotation of the nut40 with respect to the tube 38. The nut 40, ring 60 and depending endportion of the tube 38 are transversely line drilled, as at 61, for thepurposes more fully explained hereinbelow.

A tubular member 64, having a reduced depending anchor end portion 66,is secured to the depending surface of the nut 40, outwardly of the ring60, by a collar 68 welded to the nut. The wiper collar 42B, the threadedportion of the nut 40 and the tube 38 are similarly transversely linedrilled, as at 70, for the purposes more fully explained hereinbelow.

Operation When the device is to be used with a tubular string theadapter 17 is connected to the depending end of the latter and thedevice is lowered into the hole and casing 72 with the wiper unit 42threadedly connected to the nut 40. The device is positioned at aselected depth within the casing 72 and the tubing string rotated tounscrew the wiper unit from engagement with the nut 40. The springmembers of the wiper unit frictionally engage the inner surface of thecasing thus holding the wiper unit stationary while the nut isunscrewed. To insure that the parting action of the nut 40, from thewiper unit collar 42B, is easily accomplished a pair of cooperatingshoulders 74 are formed on the respective meeting surfaces or shouldersof the nut 40 and collar 42B, which prevents tight engagement of thethreaded connection. After the wiper unit has been released from the nut40, the body 12 is lowered wherein the tube 38 slides downwardly throughthe wiper unit. The upper collar 42A of the wiper unit, during thisaction, contacts the depending end of the mandrel 44 lifting the latterso that its upper end holds the cutter 30 stationary with respect to thecasing 72. Downward movement of the body 12 with respect to the cutter30 gradually moves the cutter radially outward of the body and positionsthe sharpened edge 36 of the cutter in contact with the inner wall ofthe casing. During this action the rollers 26 contact the inner wall ofthe casing opposite the cutter 30. The weight of the tubular string maythen be used to further lower the body 12 thus forcing the cutteroutwardly through the casing wall by the inclination of the cutteropening 22. The rollers 26 reduce the frictional resistance between thebody 12 and the casing wall. At the upper limit of its movement withinthe opening 22 the cutter 30 projects outwardly through the casing Wallforming an opening therein of substantial size and similarly penetratesany cement 74 surrounding the easing and if the original bore hole ispositioned adjacent the Casing, the cutter 30 penetrates the sand or oilbearing formation 76. The cutter is withdrawn from its casingpenetrating position by upward movement of the body 12. A conventionalweight indicator at the surface of the earth indicates when the devicehas completed its casing perforating action and is released from contactwith the casing.

After forming one opening in the casing, the tubing string is rotateduntil the spring-loaded pin 52 contacts the next groove 50, thereafterthe body 12 is again lowered to engage the cutter 30 with the casing ata new position. After perforating a selected number of holes in thecasing, the tool may be withdrawn from the well, or, if it is desired toperforate the casing at a deeper position, the body may be rotated toengage the collar 42B with the nut 40 to prevent actuation of the cutter30 during the downward movement. After perforating the casing it issometimes desired to circulate fluid through the device which may beaccomplished by the bores and channels disclosed hereinabove.

When it is desired to run the device 10 on a wire line, the adapter 17is connected to the depending end of conventional cable tool jars, orthe like, not shown, which are connected in a conventional manner to thewire line. In this arrangement the alternate embodiment, disclosed byFIG. 5, is used wherein a shear pin 78 is inserted into the bore 70 thuspreventing rotation of the wiper unit 42 with respect to the nut 40. Thedevice 10 is lowered into the well until the anchor 66 contacts thebottom of a hole or a bridge placed therein. Further downward movementof the tool by its weight or the cable tool jars, shears the pin 78. Thedevice is then moved up within the casing to a selected location. Thecasing is then perforated in the manner disclosed hereinabove for usewith the tubing string with the exception that downward movement of thebody 12 to perform the perforating action, is obtained by jarring on theupper end of the body with the conventional cable tool jars. When thealternate arrangement, illustrated in FIG. 5, is used with a tubularstring, the tubular member 64 and anchor 66 are normally omitted and apin 80 is inserted into the transverse bore 61 thus locking the nut 40to the tube 3,8 so that the wiper unit may be unscrewed from the nut 40.

An important feature of the operation of the device is that downwardmovement of the body 12 changes the thrust applied to the body to athrust of the cutter in a lateral right angle direction with respect tothe longitudinal axis of the body. This results in a thrust ratio ofapproximately 12 to l applied to the cutter. The cutter is forcedoutwardly through the casing wall in a punching action rather than acasing ripping action which eliminates vibration of the casing and aresulting loosening or rupture of the bond between the cement and theouter surface of the casing. This is desirable for the reason that ifthe cement bond is broken subsequent treating of the oil bearingformation, through the perforations, as by acidizing, results in a lossof the effectiveness of the acid by the circulation of the acid up anddown the outer wall of the casing.

It is desirable that the side of the body containing the slot and cutterbe positioned as closely as feasible to the inner wall of the casing tobe perforated. To accomplish this the rollers 26 are formed in pairs,each pair having different diameters than other pairs so that a pairl ofthe rollers may be used which will contact the inner wall of the casingand position the cutter side of the body close to the inner wall of thecasing.

Obviously the invention is susceptible to some change or alterationwithout defeating its practicability, and I therefore do not wish to beconfined to the preferred embodiment shown in the drawings and describedherein,

further than I am limited by the scope of the appended claims.

I claim:

1. A casing perforator adapted to be lowered into a cased well,comprising: an elongated body havingy a fluid passageway therethrough,said body having a slot parallel to the longitudinal axis of the bodyand opening outwardly of the body throughout its length, the bottomportion of the slot being T-shaped and extending diagonally with respectto and intersecting the longitudinal axis of the body; antifrictionmeans carried by said body on that side opposite the T-shaped slot; acutter having a blade portion normal to the longitudinal axis of thebody and having a T-shaped base portion cooperatively received slidablyby the slot and permitting downward movement of the body relative to thecutter when the latter is posi tioned against a casing wall; a tubularmember connected with said body in depending relation; a casing engagingfrictional wiper surrounding said tubular member and releasably engagedwith the lower end thereof; and a mandrel slidably carried vertically bythe depending end of said body and engageable with the upper end of saidwiper upon downward movement of said body and holding said cutterstationary with respect to the casing as said body is lowered, wherebysaid cutter blade is moved transversely of said body into an extendedposition outwardly of the body during continued downward movement ofsaid body.

2. Structure as specified in claim 1 in which said antifriction meansincludes: a pair of horizontal axles carried by said body adjacent itsrespective end portions on that side opposite said cutter, a rollerjournaled by each said axle, said rollers each having a peripheralsurface projecing outwardly of the cylindrical plane of said body andcooperatively contacting an arc of the inner wall of a casing forholding that side of said body having the slot adjacent the inner wallof a casing to be perforated.

3. A casing perforator, comprising: an elongated vertically disposedbody having a threaded upper end for connection with a tubular string;an elongated tube member of reduced diameter with respect to said bodyand connected with the latter in depending relation, said body having anelongated longitudinally disposed slot parallel to the longitudinal axisof the body and opening outwardly of the body throughout its length, thebottom portion of the slot being T-shaped in horizontal cross sectionand extending diagonally with respect to the longitudinal axis of saidbody, from a point adjacent the periphery of the body at its upper endportion to a point intersecting the longitudinal axis of the body at itslower end portion; a T-shaped cutter slidably received by said slot,said cutter having a blade portion normal to the longitudinal axis ofsaid body and adapted to penetrate a casing; antifriction meansconnected with the respective end portions of said body opposite theelongated slot; wiper means mounted on the depending end portion of saidtube and releasably connected thereto permitting vertical slidingmovement of the latter with respect to said wiper means; and a mandrelextended vertically through the lower end portion of said body andcommunicating with the lowermost portion of said slot for holding saidcutter stationary with respect to the casing to be perforated when themandrel is urged upwardly by contact with said wiper means as the bodyis moved downwardly, whereby said cutter blade is moved transversely ofsaid body into an extended position during continued downward movementof said body.

4. Structure as specied in claim 3 in which said body is provided with asocket adjacent its respective ends on that side opposite the cutterslot and in which said antifriction means includes a substantiallybarrel shaped roller within the respective socket, horizontal axlesconnected with said body journaling the respective said roller, aperipheral portion of each said roller projecting outwardly of thecylindrical plane defined by said body in rolling contact with the innerwall of a casing and holding that side of said body having the slotadjacent the inner wall of a casing to be perforated.

5. Structure as specified in claim 4 in which said wiper means includesupper and lower collars loosely surrounding said tube, a plurality ofoutwardly bowed spring members frictionally contacting the inner surfaceof a casing and interconnecting said collars in vertically spacedrelation, said lower collar having a threaded bore, and a nut having athreaded exterior secured to the depending end of said tube forthreadedly engaging said lower collar.

References Cited bythe Examiner UNITED STATES PATENTS 1,125,513 1/15Graham 166-55.3 1,841,500 1/32 Shull 166-553 2,152,008 3/39 Yarbrough166-55.3

CHARLES E. OCONNELL, Primary Examiner.

1. A CASING PERFORATOR ADAPTED TO BE LOWERED INTO A CASED WELL,COMPRISING: AN ELONGATED BODY HAVING A FLUID PASSAGEWAY THERETHROUGHSAID BODY A SLOT PARALLEL TO THE LONGITUDINAL AXIS OF THE BODY ANDOPENING OUTWARDLY OF THE BODY THROUGHOUT ITS LENGTH, THE BOTTOM PORTIONOF THE SLOT BEING T-SHAPED AND EXTENDING DIAGONALLY WITH RESPECT TO ANDINTERSECTING THE LONGITUDINAL AXIS OF THE BODY; ANTIFRICTION MEANSCARRIED BY SAID BODY ON THAT SIDE OPPOSITE THE T-SHAPED SLOT; A CUTTERHAVING A BLADE PORTION NORMAL TO THE LONGITUDINAL AXIS OF THE BODY ANDHAVING A T-SHAPED BASE PORTION COOPERATIVELY RECEIVED SLIDABLY BY THESLOT AND PERMITTING DOWNWARD MOVEMENT OF THE BODY RELATIVE TO THE CUTTERWHEN THE LATTER IS POSITIONED AGAINST A CASING WALL; A TUBULAR MEMBERCONNECTED